package redBlacktree;

import java.util.ArrayList;

public class RBTree<K extends Comparable<K>,V>{

    private static final boolean RED = true;
    private static final boolean BLACK = false;

    private class Node{
        public K key;
        public V value;
        public Node left,right;
        public boolean color;


        public Node(K key,V value){
            this.key = key;
            this.value = value;
            left = null;
            right = null;
            color = RED;
        }
    }

    private Node root;
    private int size;

    public RBTree(){
        root = null;
        size = 0;
    }
    public int getSize() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    //判断节点的颜色
    public boolean isRed(Node node){
        if(node == null)
            return BLACK;
        return node.color;
    }

    //  判断该二叉树是否是一颗二分搜索树
//    public boolean isBST(){
//        ArrayList<K> keys = new ArrayList<>();
//        inOrder(root,keys);
//        for(int i = 0; i < keys.size(); i++){
//            if(keys.get(i-1).compareTo(keys.get(i)) > 0)
//                return false;
//        }
//        return true;
//    }

//    private void inOrder(Node node,ArrayList<K> keys){
//        if(node == null){
//            return;
//        }
//
//        inOrder(node.left,keys);
//        keys.add(node.key);
//        inOrder(node.right,keys);
//    }

    // 判断该二叉树是否是一个平衡二叉树
//    public boolean isBalanced() {
//        return isBalanced(root);
//    }
//
//    private boolean isBalanced(Node node){
//        if (node == null) {
//            return true;
//        }
//
//        int balanceFactor = getBalanceFactor(node);
//        if(Math.abs(balanceFactor) > 1)
//            return false;
//        return isBalanced(node.left) && isBalanced(node.right);
//    }

    //获得节点的高度
//    private int getHeight(Node node){
//        if(node == null)
//            return 0;
//        return node.height;
//    }
//
//    private int getBalanceFactor(Node node){
//        if(node == null){
//            return 0;
//        }
//        return getHeight(node.left)-getHeight(node.right);
//    }

    //向右旋转
//    private Node rightRotate(Node y){
//        Node x = y.left;
//        Node T3 = x.right;
//
//        // 向右旋转过程
//        x.right = y;
//        y.left = T3;
//
//        //更新height
//        y.height = Math.max(getHeight(y.left),getHeight(y.right)) + 1;
//        x.height = Math.max(getHeight(x.left),getHeight(x.right)) + 1;
//        return x;
//    }

    //向左旋转
    private Node leftRotate(Node node){
        Node x = node.right;

        //左旋转
        node.right = x.left;
        x.left = node;

        x.color = node.color;
        node.color = RED;

        return x;
    }

    //向右旋转
    private Node rightRotate(Node node){
        Node x = node.left;

        //左旋转
        node.left = x.right;
        x.right = node;

        x.color = node.color;
        node.color = RED;

        return x;
    }

    //颜色翻转
    private void flipColors(Node node){
        node.color = RED;
        node.left.color = BLACK;
        node.right.color = BLACK;
    }
    

    //向红黑树中插入元素(key,value)
    public void add(K key, V value) {
        root = add(root,key,value);
        root.color = BLACK;
    }



    //向以node为根的红黑树中插入元素key,value，递归实现
    //返回插入新节点的红黑树的根
    private Node add(Node node,K key, V value){
        if(node == null){
            size ++;
            return new Node(key,value);//默认插入红色节点
        }
        if(key.compareTo(node.key) < 0){
            node.left = add(node.left,key,value);
        }else if(key.compareTo(node.key) > 0){
            node.right = add(node.right,key,value);
        }else{
            node.value = value;
        }

        if(isRed(node.right) && !isRed(node.left))
            node = leftRotate(node);

        if(isRed(node.left) && !isRed(node.left.left))
            node = rightRotate(node);

        if(isRed(node.left) && !isRed(node.right))
            flipColors(node);

        return node;
    }



    public V remove(K key) {
        Node node = getNode(root,key);
        if(node != null){
            root = remove(root,key);
            return node.value;
        }

        return null;
    }


    //删除以Node为根的二分搜索树中键为key的节点，递归算法
    //返回删除节点后新的二分搜索树的根
    private Node remove(Node node ,K key){
        if(node == null){
            return null;
        }

        Node retNode;
        if(key.compareTo(node.key) < 0){
            node.left = remove(node.left,key);
            retNode = node;
        }else if(key.compareTo(node.key) > 0){
            node.right = remove(node.right,key);
            retNode = node;
        }else{ //e == node.e`
            //待删除节点左子树为空的情况
            if(node.left == null){
                Node rightNode = node.right;
                node.right = null;
                size--;
                retNode = rightNode;
            }

            if(node.right == null){
                Node leftNode = node.left;
                node.left = null;
                size --;
                retNode = leftNode;
            }

            //待删除的节点左右字树均不为空的情况
            //找到比待删除节点大的最小节点，即待删除几点的右子树的最小节点
            //用这个节点替待待删除节点的位置
            Node successor = minimum(node.right);
            successor.right = remove(node.right,successor.key);
            successor.left = node.left;
            node.left = node.right = null;
            retNode = successor;
        }

        if(retNode == null)
            return null;

        return retNode;

    }

    //删除以node为根的二分搜索树中的最小节点
    //返回删除节点后新的二分搜索树的根
    private Node removeMin(Node node){
        if(node.left == null){
            Node rightNode = node.right;
            node.right = null;
            size --;
            return rightNode;
        }
        node.left = removeMin(node.left);
        return node;
    }

    private Node minimum(Node node){
        if(node.left == null){
            return node;
        }
        return minimum(node.left);
    }

    public boolean contains(K key) {
        return getNode(root,key) !=null;
    }

    public V get(K key) {
        Node node = getNode(root,key);
        return node == null ? null : node.value;
    }

    public void set(K key, V newValue) {
        Node node = getNode(root,key);
        if(node == null){
            throw new IllegalArgumentException("does not exisit");
        }
        node.value = newValue;
    }


    //返回以node为根结点的二分搜索树key所在节点
    private Node getNode(Node node,K key){
        if(node == null){
            return null;
        }
        if(key.compareTo(node.key) == 0){
            return node;
        }else if(key.compareTo(node.key) < 0){
            return node;
        }else {
            return getNode(node.right,key);
        }

    }


}
